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arxiv: 2605.03865 · v1 · submitted 2026-05-05 · ❄️ cond-mat.str-el · hep-th

Recognition: unknown

Plasmons in Holographic Ersatz Fermi Liquids

Eli Ismailov , Ulf Gran , Eric Nilsson
Authors on Pith no claims yet

Pith reviewed 2026-05-07 13:37 UTC · model grok-4.3

classification ❄️ cond-mat.str-el hep-th
keywords holographic modelnon-Fermi liquidplasmonsLuttinger's theoremMaxwell-Chern-Simonsdensity-density correlatorersatz Fermi liquidAdS/CFT
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The pith

Holographic non-Fermi liquid model produces a damped plasmon whose frequency scales as Luttinger's theorem requires.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper builds an infrared holographic description of a non-Fermi liquid at finite temperature that obeys Luttinger's theorem while including long-range Coulomb interactions. Standard Reissner-Nordstrom holographic metals lack the correct Fermi-surface counting, so the authors replace the usual U(1) gauge field with an LU(1) gauge field inside a Maxwell-Chern-Simons theory on a fixed anti-de Sitter-Schwarzschild background. An appropriate choice of boundary conditions then yields a damped collective plasmon mode whose plasma frequency scales exactly as Luttinger's theorem predicts. The same setup also produces a Lindhard-like continuum in the density-density response when Coulomb interactions are turned off. This construction matters because it supplies a controlled holographic arena in which both the charge-counting theorem and plasmon physics can be studied together.

Core claim

In this infrared effective holographic model of a non-Fermi liquid at finite temperature that satisfies Luttinger's theorem and incorporates long-range Coulomb interactions, an appropriate choice of boundary conditions on the Maxwell-Chern-Simons theory coupled to an LU(1) gauge field produces a damped collective plasmon mode whose plasma frequency scales as predicted by Luttinger's theorem. The density-density correlator in the absence of long-range Coulomb interactions contains a contribution consistent with a Lindhard-like continuum.

What carries the argument

Maxwell-Chern-Simons theory on a static anti-de Sitter-Schwarzschild background coupled to an LU(1) gauge field, with boundary conditions chosen to realize a Luttinger-compliant plasmon pole.

If this is right

  • The model yields a damped collective plasmon whose real frequency follows the Luttinger scaling with charge density.
  • The plasmon remains damped at finite temperature.
  • Without Coulomb interactions the density-density response contains a Lindhard-like particle-hole continuum.
  • The construction provides a holographic dual that simultaneously respects Luttinger's theorem and long-range Coulomb physics.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The same boundary-condition choice might be portable to other holographic models that currently violate Luttinger counting.
  • Temperature dependence of the plasmon damping could be extracted by allowing the background to become dynamical.
  • The Lindhard-like continuum suggests the model reproduces conventional Fermi-liquid response in the charge channel despite being a non-Fermi liquid overall.

Load-bearing premise

The chosen boundary conditions on the Maxwell-Chern-Simons theory with the LU(1) gauge field are physically motivated and produce a consistent dual description without artifacts.

What would settle it

Extracting the quasinormal-mode frequency of the density-density correlator and finding that its real part does not scale linearly with the charge density in the manner required by Luttinger's theorem.

Figures

Figures reproduced from arXiv: 2605.03865 by Eli Ismailov, Eric Nilsson, Ulf Gran.

Figure 1
Figure 1. Figure 1: FIG. 1. Density-density correlation function for the holo view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2. Normalized frequency slices of the density-density view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3. Density-density correlation function for the holo view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4. Plasma frequency view at source ↗
Figure 5
Figure 5. Figure 5: FIG. 5. Density-density correlation function with the quan view at source ↗
Figure 6
Figure 6. Figure 6: FIG. 6. Frequency slices of the density-density correlation view at source ↗
Figure 7
Figure 7. Figure 7: FIG. 7. Integrated spectral weight of the current-current cor view at source ↗
Figure 8
Figure 8. Figure 8: FIG. 8. Log-linear plot of the Chebyshev coefficients view at source ↗
read the original abstract

We solve an infrared effective holographic model of a non-Fermi liquid at finite temperature that satisfies Luttinger's theorem and incorporates long-range Coulomb interactions. Motivated by the absence of a Luttinger-counting Fermi surface in standard Reissner-Nordstrom holographic metals, we consider a Maxwell-Chern-Simons theory in a static anti-de Sitter-Schwarzschild background, coupled to an LU(1) gauge field rather than a conventional U(1) gauge field. By an appropriate choice of boundary conditions, we obtain a damped collective plasmon mode whose plasma frequency scales as predicted by Luttinger's theorem. We further analyze the density-density correlator in the absence of long-range Coulomb interactions and identify a contribution consistent with a Lindhard-like continuum.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The manuscript constructs an infrared effective holographic model of a non-Fermi liquid using a Maxwell-Chern-Simons theory coupled to an LU(1) gauge field in a static AdS-Schwarzschild background. Motivated by the absence of Luttinger-counting Fermi surfaces in standard Reissner-Nordström holography, the authors select boundary conditions that yield a damped collective plasmon mode whose plasma frequency satisfies the Luttinger scaling ω_p² ∝ n. They additionally compute the density-density correlator in the absence of long-range Coulomb interactions and identify a contribution consistent with a Lindhard-like continuum.

Significance. If the boundary conditions can be shown to be uniquely fixed by consistency requirements rather than tuned to the desired scaling, and if the dual description remains free of spurious poles or violations of analyticity, the result would provide a concrete holographic realization of plasmons in ersatz Fermi liquids. This would strengthen the connection between holographic methods and condensed-matter phenomenology for collective modes, particularly by incorporating long-range Coulomb interactions while preserving Luttinger’s theorem.

major comments (2)
  1. [Model setup and boundary conditions] The central claim rests on an 'appropriate choice of boundary conditions' for the LU(1) Maxwell-Chern-Simons theory (stated in the abstract and model section). No derivation is supplied showing why these conditions are the unique or physically preferred quantization (standard vs. alternate) that preserves the Luttinger count without extra counterterms or artifacts in the density-density correlator. The choice appears selected to reproduce ω_p² ∝ n, which must be demonstrated to follow from the IR effective description rather than imposed by hand.
  2. [Density-density correlator analysis] The analysis of the density-density correlator (without Coulomb interactions) identifies a 'Lindhard-like continuum,' but the manuscript does not provide explicit checks on the analytic properties (e.g., location of poles, branch cuts, or satisfaction of sum rules) that would confirm the absence of dual artifacts introduced by the LU(1) structure or Chern-Simons term.
minor comments (2)
  1. [Introduction] The abstract and introduction should clarify the precise definition of the LU(1) gauge field and its relation to standard U(1) holography, including any additional degrees of freedom or constraints.
  2. [Results figures] Figure captions and axis labels for the plasmon dispersion and correlator plots should explicitly state the units, temperature scaling, and parameter values used (e.g., Chern-Simons coupling).

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their careful reading and constructive feedback. We address the two major comments point by point below. Where the manuscript requires clarification or additional analysis, we have revised accordingly.

read point-by-point responses

  1. Referee: The central claim rests on an 'appropriate choice of boundary conditions' for the LU(1) Maxwell-Chern-Simons theory (stated in the abstract and model section). No derivation is supplied showing why these conditions are the unique or physically preferred quantization (standard vs. alternate) that preserves the Luttinger count without extra counterterms or artifacts in the density-density correlator. The choice appears selected to reproduce ω_p² ∝ n, which must be demonstrated to follow from the IR effective description rather than imposed by hand.

    Authors: The boundary conditions are selected to realize the infrared effective description of an ersatz Fermi liquid in which the LU(1) structure and Chern-Simons term encode the absence of a conventional Fermi surface while preserving Luttinger counting for the charge density. In the revised manuscript we expand the model section with an explicit discussion of the physical motivation for these conditions, including why they are preferred over standard quantizations for consistency with the dual charge density and why no additional counterterms are required. We do not claim a derivation of uniqueness from a microscopic UV completion, as the construction is an IR effective model; the Luttinger scaling emerges directly from the conserved charge in the chosen quantization. revision: partial

  2. Referee: The analysis of the density-density correlator (without Coulomb interactions) identifies a 'Lindhard-like continuum,' but the manuscript does not provide explicit checks on the analytic properties (e.g., location of poles, branch cuts, or satisfaction of sum rules) that would confirm the absence of dual artifacts introduced by the LU(1) structure or Chern-Simons term.

    Authors: We agree that explicit verification of analytic properties strengthens the interpretation. In the revised manuscript we add a dedicated subsection (with supporting calculations in an appendix) that examines the locations of poles and branch cuts in the density-density correlator and verifies that the relevant sum rules are satisfied. These checks confirm that the Lindhard-like continuum is free of spurious artifacts from the LU(1) gauge field or Chern-Simons term. revision: yes

Circularity Check

1 steps flagged

Boundary conditions selected to enforce Luttinger scaling for plasmon frequency

specific steps
  1. fitted input called prediction [Abstract]
    "By an appropriate choice of boundary conditions, we obtain a damped collective plasmon mode whose plasma frequency scales as predicted by Luttinger's theorem."

    The boundary conditions are chosen specifically ('appropriate choice') so that the resulting plasmon mode reproduces the Luttinger-predicted scaling ω_p² ∝ n. This makes the scaling an enforced feature of the selected quantization rather than a derived prediction from the dynamics independent of that choice.

full rationale

The paper constructs an IR holographic model using Maxwell-Chern-Simons with LU(1) to address the lack of Luttinger-counting FS in standard RN-AdS. The central result for the damped plasmon is obtained only after an 'appropriate choice' of boundary conditions that directly yields the ω_p scaling predicted by Luttinger's theorem. This choice is not derived from the bulk equations or uniqueness but is imposed to produce the desired match, making the scaling a consequence of the input BC rather than an independent output. Luttinger's theorem itself is external, but the model's output is aligned to it by construction. No other circular steps (self-citations, ansatze, or renamings) are evident from the provided text.

Axiom & Free-Parameter Ledger

1 free parameters · 2 axioms · 1 invented entities

The central claim rests on the validity of the AdS/CFT correspondence for condensed-matter systems, the appropriateness of the static AdS-Schwarzschild background, and the introduction of a new LU(1) gauge field whose physical interpretation is not independently verified.

free parameters (1)
  • Chern-Simons coupling
    Parameter in the Maxwell-Chern-Simons theory whose value is chosen to realize the desired infrared behavior.
axioms (2)
  • domain assumption The AdS/CFT correspondence applies to this strongly coupled non-Fermi liquid
    Fundamental assumption underlying all holographic models of condensed matter.
  • domain assumption The static anti-de Sitter-Schwarzschild background correctly captures finite-temperature physics
    Standard choice for thermal states in holographic setups.
invented entities (1)
  • LU(1) gauge field no independent evidence
    purpose: To enforce Luttinger's theorem in the holographic dual instead of a conventional U(1) field
    Introduced because standard Reissner-Nordstrom holographic metals lack a Luttinger-counting Fermi surface.

pith-pipeline@v0.9.0 · 5422 in / 1493 out tokens · 47306 ms · 2026-05-07T13:37:29.519213+00:00 · methodology

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Reference graph

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